Stretch breaking apparatus and method



y ,1 D. G. ,c. HARE 2,638,634

- STRETCH BREAKING APPARATUS AND METHOD Filed June 20, 1947 INVENTOR Dom/*0 c. c. HARE M I ORNEY/ Patented May 19, 1953 umrrco Pars-NT orrrcr;

sgayncmBnEA-KING APPARATUS AND ME O Donald G. czyHa're, (Clemson, 'S.) (35., assignor' to Peering Milliken -Research Trust, New York, N. Y.;--a nonprofittrust 1 of New York ApplicatiqnJu-ne 20, 194'Z, -Ser.ial-No. 7564169 5 Glaims; (Cl. "193- 0237 Thehresentinvention relates. to.- the treatment of continuous textile. filaments ior production. of sliver, roving or yarn i therefrom and comp ises animproved stretch breakin Process, :andmeans, for conversion of a tow of continuoushfilarnents, such. as rayonvv tow, into, a. staple i fiber product, of superior quality. The invention. is 1. particularly adaptedfior the? treatment of. rayon tow,.-w-hether of regenerated cellulose-such as viscosa, or.of an organic. derivative .ot cellulosa, suchas ce1=1u-. lose. acetate and will accordingly be-describedwith reference, to. such applicat .Theimethcd; of the-invention'is applicable, however, to) any type of. textile filamentaryvmaterial that maybe-weak encd y heat.

Conyersioncf rayontow inta'staphfibers by stretch. b e kin :he etoic erp ac iccd the art ol s-thegr nn sthe tcwibywat least two s ts of tat n ollsmt wh ch. onc;-set,.he deiiv y ets ro ates a a; h herrgperipheral; speed than that. of; the other, 1 or teed set, with 09115. 3 quaint, breakinsot the individnalaxfilaments :or the w during pa sa e-tram the feed tathe dehverir rolls. one; of: the numerous; drafting 'mechani msordinarily,used-in the; textile; industrycfor ii-netting.- staplafiber: sliver: and noving'instheiprot. dnction ofwyarrror .fonliedlicihgsz fiber: lengtn'by stretch breaking can; be used. 130E stretcm breakinatow. Such.treatmentofiacontinuous.filaments ina draiitingmechanism-is;intcndecrtoccauseithe filamentszto; break randomly atxdifierent positions in; the .ratch; with corresponding randomlength ofx,.staple fibers; in: the produced roving-r our-yarn and consecuent isubstantialo uniformity':-'-ot tl-1e product. Such. intended action. 1 however; does not; materialize, in practiceas :filamen-t breakage; instead :bein randomly distributed in the catch, iscdisproportionately i large near =-the-draft or delivery rolls. This results in midesiredi short staple length ot fibers ln' th 1 Vi'l-1-g- 01 5 8128? The concentration of: filament breakage-inthe lower partzoi athe. ratchi is b elicvexi' due to inter-filament friction which reducestthe efiiective -lcngthof the rat-ch...

' .When; filaments break-near the lower-rolls; the ends. of: those: lengths ot filaments u held only" by the upper rolls tend to snap up and out of the sliveriand drag-with them-ends of otherfilaments which may have-been broken higherin the-'ratch and arebeingadvanced bythe rotation ofthe feedi rolls. --'I'here is thuspresented'to the 'nips ot the draftrol-ls a relativelythin portionof sliver corresponding to---'the----portion "from-'whicl'jr the broken ends have snapped bacl; Thisi's folioweld bya thicker-portionin which there is aplurality '2; of frayed or broken ends turned back upon the sliveror. projecting from the side thereof. The result is improper drafting. and the production of slubby roving or yarn. The succession of relatiyeiy thinv and thickportions of silver in the ratch caused by the concentration of fiber breakage near the lower rolls, occurs cyclically, giving a breathing action to. thedrafting and result.- ing-ina yarn orwroving of periodically varying diameter.

A further disadvantage in the conversion of rayon tow to roving or toyarnby stretch. break.- ing asv heretofore practiced isv that-thev physical characteristics. of Y the cellulosic. materials may be impaired by the. necessary stretching of the filaments .beyondtheir elastic limit.

Objectsof the invention are, therefore, to provide a method of stretch breakingtow that. will 7 parted to the tow to cause such. ofthe filaments asare under tension to break where heated. The temperature ofthe rolls should not be sohigh thatfi-lamentsnotunder tension, that is: filaments not gripped by both draft, and teed rolls, reak apart or attenuate substantially. With rayon tow, either-acetate or :viscose, temperatures obtained by heating the feed rolls with steam or superheated steam hayeibecn found satisfactory.

In; the accompanying. drawings:

Fig. 1'. is a diagrammatic view of a tow stretch breaking mechanism showingthe idler feed roll heatediinu-accordance.with. the invention;

- 'Fig..2:.is'a longitudinal sectional vicw, partly in elevation of the heated .icllerfeedroll of Fig. i. Fig. 2a is a--view-'-corresponding to Fig. 2' but showing aheated driyen feed roll. i

Fig. 3 isa side-viewof a heated feed rollrepresenting-a modification wherein steam-is injected into the tow a-nd- Fig; 4 lea-transverse"sectional'viewtaken on thel1ine-4-4 of Fig. 3.

In- 'Fig. 1-, a tow stretch breaking "mechanism isdiagrammaticaliy illustrated as comprising a pair of feed rolls 2 and 4 and a pair of draft or tensioning rolls 6 and 8. As in the usual drafting mechanism one roll of each pair is driven, and. the other roll of each pair is an idler roll; rolls 6 and 8 rotate at a substantialy higher rate than rolls 2 and 4 to exert tension on filaments held by both pairs of rolls. Rotation of the feed rolls 2 and :2. draws tow 10 from any suitable sup ply source (not shown) and feeds it into the ratch defined by the two pairs of rolls. When the forward ends of the filaments of the tow are seized by the rapidly rotating draft rolls, sufficient tension is applied to cause breakage of the filaments into staple lengths. In accordance with the invention, one or both of the feed rolls is heated to cause filament breakag at or near the nips of the feed rolls.

In the particular embodiment of the invention illustrated in Figs. 1 and 2, idler roll 4 is heated internally by steam. For this purpose the roll 4 comprises a rotatably mounted shell l2 enclosing a stationary hollow core I4 to which steam is supplied from a pipe I6. The pipe It is rigidly connected to member I4 and serves as a support therefor. A fixed bracket [8 supports the pipe it adjacent its connection with member l4 and carries the inner race of a ball bearing 20, the outer race of which is carried by the sleeve I2; sleeve l2 being suitably flared at E2, as shown, to enclose the bearing 20. The other end of a sleeve i2 is rotatably mounted, as by ball bearing 22, on a fixed shaft 24. A small condensate return pipe is indicated at 28. With the abov described arrangement, the shell [2 will transfer heat from the steam heated core l4 to the tow ID as it enters the nips of the feed rolls,

and such filaments of the tow as are gripped by both sets of rolls will break at or near the nips of the feed rolls.

Once th stretch breaking is initiated, there is no danger of complete severance of the strand at the nips of the feed rolls as there will be in the ratch numerous ends of filaments previously broken, and such filaments will not be gripped by both sets of rolls and hence will not break at the nips of the feed rolls until their forward ends reach the nips of the draft rolls. In initiating the stretch breaking, if the advancing end of the tow is not sufficiently tapered, it may be cut on a bias so that all of the filament ends are not in alignment, or heating of the feed roll may be delayed until after som random breakage in the ratch has occurred.

Instead of heating the idler roll, as described in connection with Figs. 1 and 2, the driven roll 2 could be heated, or both rolls could be heated if desired. If a driven, rather than an idler roll is to be heated, the shell [2| of the roll could be splined, as indicated in Fig. 2a, to a drive shaft 24.

The above described heating arrangement, which imparts dry heat to the tow, is particularly suitable for acetate tow which readily weakens when subjected to heat. For viscose tow which is susceptible to moisture as well as to heat, the modification of the invention illustrated in Figs. 3 and 4 is preferred.

In Figs. 3 and 4, a fluted roll 4a, which may be an ider feed roll, or a driven feed roll, is shown as comprising a shell lie within which is a tubular member We connected to the steam supply pipe E5. The tubular member 14a is provided with an elongated slot 27, and the shell I211 is provided with a plurality of radial passages 28 of substantial axial length. The slot 27 is on the side of member Ma facing the other feed roll 20. and hence, during rotation of the rolls, steam from member Ma will be ejected into the tow l0 through the passages 28 in the shell I2a. By providing a relatively close fit between the inner surface at the shell [2a and the outer surface of member 14a, ejection of steam from the roll 4acan be substantially confined to the nips of the feed rolls. The heat and moisture thus delivered to the tow will concentrate filament breakage at or near the nips as heretofore described.

This arrangement, whereby steam is ejected directly into the tow, avoids the necessity for the provision of a condensate return pipe, increases the local weakening of tow that is susceptible to moisture, such as viscose tow, and provides a vehicle, if desired, for treating agents for the tow, as for example, lubricants, crimping agents, or the like.

The invention has now been described with reference to two embodiments thereof, one particularly suitable for use with cellulose acetate tow and on particularly suitable for use with viscose tow. Although in each embodiment of the invention illustrated in the drawings, the heating agent has been indicated as steam, obviously other heating means for one or both of the feed rolls could be provided without departing from the spirit of the invention. For xample, hot gases, such as hot air, or products of combustion, could be introduced into, or played upon, one or both of the feed rolls or heat could be transferred conductively to the rolls, as by contact of their outer surfaces with stationary heating means, or the rolls could be heated electrically or subjected to radiant or dielectric heat as is disclosed and claimed in the co-pending application of Robert M. Ingham, filed June 7, 1947, Serial No. 753,197, and assigned to the assignee of this application. Preferably, as described herein, the feed rolls are continuously heated, but obviously, if desired, they could be heated intermittently, with corresponding change in length of the produced staple fibers.

While th invention has been described in connection with a direct tow-to-yarn spinner, the method and means of the invention are not concerned with the particular form of staple fiber product, that is, whether it is in the form of yarn or of roving, nor is the invention necessarily limited to the treatment of artificial, as distinguished from natural filaments or fibers as the invention may be advantageously employed for stretch breaking of any filamentary material which is thermoseverable and of a length greater than that of the ratch. The heated rolls of the invention could be utilized in any textile drafting or drawing operation if heat treatment of the material being drawn or drafted is desired.

The following is claimed:

1. The method of treatingtow which comprises stretch breaking the tow in a drafting mechanism while applying heat and moisture to the tow at the nips of the feed rolls.

2. The method according to claim 1 wherein heat and moisture are applied to the tow at the feed rolls by localized injection of steam into the tow.

3. Apparatus for converting continuous filamentary material into fibers of staple length which comprises a first and second pair of driven rolls, at least one of said first pair of rolls having a plurality of perforations therein, means for introducing a heat containing fluid-medium into the interior of said perforated roll, said medium passing through said perforations and impinging upon individual filaments passing between said rolls in order to weaken the same, and means for driving the second pair of rolls at sufilcient speed in excess of the first pair to stretch weakened filaments beyond their extensibility, whereby said stretched filaments weakened by the heated fluid break in the neighborhood of said first pair of rolls. I

4. The apparatus of claim 3 wherein said perforated roll comprises a hollow tubular axle provided with an elongated slot facing the other roll of said pair adjacent the nip and an outer shell provided with a plurality of radial passages, said shell being rotatably mounted on said axle whereby heated fluid under pressure delivered to the interior of said axle passes out through the slot and passages substantially at the nip of the first pair of rolls.

5. The process of converting substantially parallel continuous filamentary material into fibers of staple length, which comprises forwarding the material between a pair of driven holding rolls, applying heat and moisture to individual filaments in a zone adjacent said rolls to weaken the filaments and, while maintaining the parallel relationship of the filaments, subjecting them to a stretch in excess of the extensibility of the weakened filaments, whereby the weakened stretched filaments break in the neighborhood of the rolls.

DONALD G. C. HARE.

References Cited in the file of this patent UNITED STATES PATENTS 

